1. Field of the Invention
The present invention relates to a piezo-driven micro-droplet jet generator, particularly to a micro-droplet jet generator having a piezo-driven membrane and a plurality of micro-sized holes through which droplets are ejected.
2. Description of Related Art
Microelectronic technology has made great progress in recent years and is subject of intensive research and development efforts. Micro-droplet jet generators have found wide use in ink-jet printers. Since ejection speed and flow are precisely controllable, further applications of micro-droplet jet generation technology are biotechnology, micro-coating, controlling of tiny jet quantities and scent generators.
Conventional micro-droplet jet generators are mainly of two types, thermal bubble and piezoelectric jet generators. Since the present invention relates to piezoelectric technology, thermal bubble jet generators will not be mentioned further.
A piezoelectric jet generator creates electrically generated vibrations of an amplitude and a high frequency, driving a compressing element in a pressing movement, leading to the ejection of liquid through tiny nozzles. Since piezoelectric jet generators do not operate by heating liquid, there is no risk of changes in the composition of the liquid and, as compared to thermal bubble jet generators, no subsequent damage after prolonged use will occur. Therefore, a wider range of biomedical and industrial applications is attained.
Conventional piezoelectric jet generators are still in need of improvement. First, a piezoelectric jet generator has a piezoelectric elements as a main structural part, which is made of piezoelectric material. However, if piezoelectric material is exposed to etching liquid for an extended time period, piezoelectric effect thereof is diminished to the point of damaging the piezoelectric element. Therefore, conventional piezoelectric jet generators are not usable in conjunction with etching liquid.
Furthermore, conventional piezoelectric jet generators have chambers between the nozzles and the piezoelectric element. Liquid that has flown into the chambers is ejected through the nozzles due to pressure generated by the piezoelectric element. In conventional art, however, the chambers are usually far wider than the amplitude of the vibrations of the piezoelectric element, so that the vibrations change the volume of the chambers only to a small degree and little pressure is generated. For ejecting droplets, the nozzles need to have minimum sizes, not allowing for ejection of micro-sized droplets.